NOD Upgrade questions...

I have several questions regarding upgrading an existing version of NOD32. I'm currently running an older version of NOD v4 (I can't remember the exact version as of now, and am away from that machine), and am curious as to what I need to do to upgrade.

1) Is it acceptable to install a new version over an older version? Will this cause problems for me, or will I have to uninstall the older version first? If I have to uninstall, is there a way to preserve my settings?

2) Do newer versions of NOD provide increased protection, or are they simply compatibility fixes provided to resolve issues? I've not had any problems with NOD so far, so I'd like to ascribe to an 'If it's not broken, don't fix it' attitude - However, if there's a reduction in protection or scanning efficacy, obviously I would rather upgrade as soon as possible.

3) Are there any serious issues in the latest version of NOD that I ought to be aware of? I remember a while back there were numerous threads about web traffic being slowed to a crawl, and other conflicts, which some users decided to roll back to prevent. I'd rather not step on a landmine if I can avoid it.

1. Yes it is, if you are using some version within the version 4 range.
Example, 4.0 , 4.1 , 4.2 then YES it's OK to install over the older one.
And YES the settings will stay the same if you push the right buttons.